Fibroblast growth factor 21 proteins

ABSTRACT

This present invention relates to pharmacologically potent and stable human fibroblast growth factor 21 (FGF21) proteins, pharmaceutical compositions comprising FGF21 proteins, and methods for treating type 2 diabetes, obesity, dyslipidemia, and/or metabolic syndrome using such proteins.

This present invention relates to fibroblast growth factor 21 (FGF21)proteins, pharmaceutical compositions comprising FGF21 proteins, andmethods for treating type 2 diabetes, obesity, dyslipidemia, and/ormetabolic syndrome.

FGF21 is a hormone that functions as an important metabolic regulator ofglucose and lipid homeostasis. FGF21 promotes glucose uptake inadipocytes by up-regulating GLUT1 expression, a mechanism distinct fromthat of insulin. In diabetic rodents and monkeys, human FGF21 loweredfasting serum concentrations of glucose, and reduced fasting serumconcentrations of triglycerides, insulin and glucagon. Furthermore, inrodent models of diet induced obesity, FGF21 administration led tocumulative body weight loss in a dose dependent manner. Thus, FGF21 haspotential utility for the treatment of diabetes, obesity, dyslipidemia,and metabolic syndrome.

FGF21 proteins have been described in WO2010/042747, WO2010/285131, andWO2009/149171.

Problems associated with human wild type FGF21 and known FGF21 proteinsare a short half-life in vivo, a low potency and/or pharmaceuticalinstability of the molecules. Thus, there is still a need foralternative FGF21 proteins that are long-acting, potent and/or stable.

The present invention provides alternative FGF21 proteins. Certain FGF21proteins of the present invention have advantages over human wild typeFGF21 and known FGF21 proteins disclosed in the art. These advantagesinclude having an extended half-life, improved potency and/or improvedpharmaceutical stability. In addition to improved potency, certain FGF21proteins of the present invention have one or more advantageousstability characteristics that are useful for efficient manufacturingand/or formulation as a therapeutic protein, including reducedproteolytic degradation in vivo, reduced susceptibility to oxidation,lowered propensity to aggregate at high concentrations, lowered levelsof post-translational modifications and proteolysis during production inmammalian cell systems, and/or improved chemical stability.Additionally, the FGF21 proteins of the present invention arepotentially useful for the treatment of type 2 diabetes, obesity,dyslipidemia, and/or metabolic syndrome.

The present invention provides a FGF21 protein, wherein the amino acidsequence consists of a first polypeptide fused to a second polypeptide,wherein the first polypeptide comprises an IgG4 Fc portion, wherein theFc portion consists of a hinge region, CH2 and CH3 constant regiondomains of an antibody, the second polypeptide comprises a FGF21 proteinhaving the amino acid sequence of SEQ ID NO: 1, and wherein theC-terminus of the first polypeptide is fused to the N-terminus of thesecond polypeptide via a linker.

Furthermore, the present invention provides a FGF21 protein, wherein theamino acid sequence consists of a first polypeptide fused to a secondpolypeptide, wherein the first polypeptide comprises an IgG4 Fc portionhaving the amino acid sequence of SEQ ID NO: 14, the second polypeptidecomprises a FGF21 protein having the amino acid sequence of SEQ ID NO:1, and wherein the C-terminus of the first polypeptide is fused to theN-terminus of the second polypeptide via a linker.

The present invention also provides a FGF21 protein, wherein the aminoacid sequence consists of a first polypeptide fused to a secondpolypeptide, wherein the first polypeptide comprises an IgG4 Fc portionhaving the amino acid sequence of SEQ ID NO: 14, the second polypeptidecomprises a FGF21 protein having the amino acid sequence of SEQ ID NO:1, and wherein the C-terminus of the first polypeptide is fused to theN-terminus of the second polypeptide via a linker having the amino acidsequence of SEQ ID NO: 11.

The present invention provides a FGF21 protein, wherein the amino acidsequence is

(SEQ ID NO: 5) ESKYGPPCPPCPAPEAAGGPSVFLFPPKPKDTLMISRTPEVTCVVVDVSQEDPEVQFNWYVDGVEVHNAKTKPREEQFNSTYRVVSVLTVLHQDWLNGKEYKCKVSNKGLPSSIEKTISKAKGQPREPQVYTLPPSQEEMTKNQVSLTCLVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFFLYSRLTVDKSRWQEGNVFSCSVMHEALHNHYTQKSLSLSLGGGGGSGGGGSGG GGSAHPIPDSSPLLQFGGQVRQRYLYTDDAQQTECHLEIREDGTVGCAADQSPESLLQLKALKPGVIQILGVKTSRFLCQRPDGALYGSLHFDPEACSFREDLKEDGYNVYQSEAHGLPLHLPGDKSPHRKPAPRGPARFLPLPGLPPALPEPPGILAPQPPDVGSSDPLRLVEPSQLRSPSFE.

The FGF21 protein of SEQ ID NO: 5 described above includes the IgG4 Fcportion sequence of SEQ ID NO: 14, the linker sequence of SEQ ID NO: 11that is identified in bold, and the FGF21 protein of SEQ ID NO: 1 thatis underlined.

Furthermore, the present invention provides a FGF21 protein, wherein theamino acid sequence is

(SEQ ID NO: 15) ESKYGPPCPPCPAPEAAGGPSVFLFPPKPKDTLMISRTPEVTCVVVDVSQEDPEVQFNWYVDGVEVHNAKTKPREEQFNSTYRVVSVLTVLHQDWLNGKEYKCKVSNKGLPSSIEKTISKAKGQPREPQVYTLPPSQEEMTKNQVSLTCLVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFFLYSRLTVDKSRWQEGNVFSCSVMHEALHNHYTQKSLSLSLGGGGGSGGGGSGGGGSAHPIPDSSPLLQFGGQVRQRYLYTDDAQQTECHLEIREDGTVGCAADQSPESLLQLKALKPGVIQILGVKTSRFLCQRPDGALYGSLHFDPEACSFREX₁LX₂EDGYNVYQSEAHGLPLHLPGDKSPHRKPAPRGPARFLPLPGLPPALPEPPGILAPQPPDVGSSDPLRLVEPSQLX₃SPSFX₄X₅wherein X₁ is L or D, X₂ is L or K, X₃ is R or L, X₄ is L or E, and X₅is G or is absent. The present invention also provides a FGF21 proteinof SEQ ID NO: 15, wherein the X₁ is D, X₂ is L or K, X₃ is L, X₄ is L,and X₅ is G. Furthermore, the present invention provides a FGF21 proteinof SEQ ID NO: 15, wherein X₁ is L or D, X₂ is L or K, X₃ is R, X₄ is E,and X₅ is absent.

The present invention provides a FGF21 protein of SEQ ID NO: 15, whereinthe FGF21 protein is selected from the group consisting of SEQ ID NO: 5,SEQ ID NO: 6, SEQ ID NO: 7, SEQ ID NO: 8, and SEQ ID NO: 9. The presentinvention also provides a FGF21 protein of SEQ ID NO: 15, wherein theFGF21 protein is selected from the group consisting of SEQ ID NO: 8 andSEQ ID NO: 9. Furthermore, the present invention provides a FGF21protein of SEQ ID NO: 15, wherein the FGF21 protein is selected from thegroup consisting of SEQ ID NO: 5, SEQ ID NO: 6, and SEQ ID NO: 7. Themost preferred FGF21 protein is SEQ ID NO: 5.

The present invention also provides a pharmaceutical compositioncomprising a FGF21 protein of the present invention and at least onepharmaceutically acceptable carrier, diluent, or excipient.

The present invention also provides a method of treating type 2diabetes, obesity, dyslipidemia, and/or metabolic syndrome in a patientcomprising administering to the patient a FGF21 protein of the presentinvention.

The present invention also provides a method of treating type 2diabetes, obesity, dyslipidemia, and/or metabolic syndrome in a patientcomprising administering to the patient a pharmaceutical composition ofthe present invention.

Furthermore, the present invention provides a FGF21 protein of thepresent invention for use in therapy. Preferably, the present inventionprovides a FGF21 protein of the present invention for use in thetreatment of type 2 diabetes, obesity, dyslipidemia, and/or metabolicsyndrome.

Furthermore, the present invention provides the use of a FGF21 proteinof the present invention in the manufacture of a medicament for thetreatment of type 2 diabetes, obesity, dyslipidemia, and/or metabolicsyndrome.

The present invention also relates to polynucleotides encoding theabove-described FGF21 protein of the present invention.

Furthermore, the present invention provides a polynucleotide encodingthe FGF21 protein of the present invention, wherein the amino acidsequence of the FGF21 protein consists of a first polypeptide fused to asecond polypeptide, wherein the first polypeptide comprises an IgG4 Fcportion, wherein the Fc portion consists of a hinge region, CH2 and CH3constant region domains of an antibody, the second polypeptide comprisesa FGF21 protein having the amino acid sequence of SEQ ID NO: 1, andwherein the C-terminus of the first polypeptide is fused to theN-terminus of the second polypeptide via a linker.

The present invention also provides a polynucleotide encoding the FGF21protein of the present invention, wherein the amino acid sequence of theFGF21 protein consists of a first polypeptide fused to a secondpolypeptide, wherein the first polypeptide comprises an IgG4 Fc portionhaving the amino acid sequence of SEQ ID NO: 14, the second polypeptidecomprises a FGF21 protein having the amino acid sequence of SEQ ID NO:1, and wherein the C-terminus of the first polypeptide is fused to theN-terminus of the second polypeptide via a linker.

Furthermore, the present invention provides a polynucleotide encodingthe FGF21 protein of the present invention, wherein the amino acidsequence of the FGF21 protein consists of a first polypeptide fused to asecond polypeptide, wherein the first polypeptide comprises an IgG4 Fcportion having the amino acid sequence of SEQ ID NO: 14, the secondpolypeptide comprises a FGF21 protein having the amino acid sequence ofSEQ ID NO: 1, and wherein the C-terminus of the first polypeptide isfused to the N-terminus of the second polypeptide via a linker havingthe amino acid sequence of SEQ ID NO: 11.

Furthermore, the present invention provides a polynucleotide encodingthe FGF21 protein of the present invention, wherein the amino acidsequence of the FGF21 protein is

(SEQ ID NO: 5) ESKYGPPCPPCPAPEAAGGPSVFLFPPKPKDTLMISRTPEVTCVVVDVSQEDPEVQFNWYVDGVEVHNAKTKPREEQFNSTYRVVSVLTVLHQDWLNGKEYKCKVSNKGLPSSIEKTISKAKGQPREPQVYTLPPSQEEMTKNQVSLTCLVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFFLYSRLTVDKSRWQEGNVFSCSVMHEALHNHYTQKSLSLSLGGGGGSGGGGSGGGGSAHPIPDSSPLLQFGGQVRQRYLYTDDAQQTECHLEIREDGTVGCAADQSPESLLQLKALKPGVIQILGVKTSRFLCQRPDGALYGSLHFDPEACSFREDLKEDGYNVYQSEAHGLPLHLPGDKSPHRKPAPRGPARFLPLPGLPPALPEPPGILAPQPPDVGSSDPLRLVE PSQLRSPSFE.

The present invention also provides a polynucleotide encoding the FGF21protein of the present invention, wherein the nucleotide sequence is SEQID NO: 13.

The polynucleotides encoding the above-described proteins may be in theform of RNA or in the form of DNA, which DNA includes cDNA, andsynthetic DNA. The DNA may be double-stranded or single-stranded. Thecoding sequences that encode the proteins of the present invention mayvary as a result of the redundancy or degeneracy of the genetic code.

The polynucleotides that encode for the proteins of the presentinvention may include the following: only the coding sequence for theproteins, the coding sequence for the proteins and additional codingsequence, such as a leader or secretory sequence or a pro-proteinsequence; the coding sequence for the proteins and non-coding sequence,such as introns or non-coding sequence 5′ and/or 3′ of the codingsequence for the proteins. Thus the term “polynucleotide encoding aprotein” encompasses a polynucleotide that may include not only codingsequence for the proteins but also a polynucleotide that includesadditional coding and/or non-coding sequence, such as SEQ ID NO: 13.

The polynucleotides of the present invention will be expressed in a hostcell after the sequences have been operably linked to an expressioncontrol sequence. The expression vectors are typically replicable in thehost organisms either as episomes or as an integral part of the hostchromosomal DNA. Commonly, expression vectors will contain selectionmarkers, e.g., tetracycline, neomycin, and dihydrofolate reductase, topermit detection of those cells transformed with the desired DNAsequences.

The FGF21 proteins of the present invention may readily be produced inmammalian cells such as CHO, NS0, HEK293 or COS cells; in bacterialcells such as E. coli, Bacillus subtilis, or Pseudomonas fluorescence;or in fungal or yeast cells. The host cells are cultured usingtechniques well known in the art. The preferred mammalian host cell isthe CHOK1SV cell line containing a glutamine synthetase (GS) expressionsystem (see U.S. Pat. No. 5,122,464).

The vectors containing the polynucleotide sequences of interest (e.g.,the proteins of FGF21 and expression control sequences) can betransferred into the host cell by well-known methods, which varydepending on the type of cellular host. For example, calcium chloridetransformation is commonly utilized for prokaryotic cells, whereascalcium phosphate treatment or electroporation may be used for othercellular hosts.

Various methods of protein purification may be employed and such methodsare known in the art and described, for example, in Deutscher, Methodsin Enzymology 182: 83-89 (1990) and Scopes, Protein Purification:Principles and Practice, 3rd Edition, Springer, N.Y. (1994).

The present invention also provides a process for producing a homodimerwherein the amino acid sequence of each polypeptide of said homodimer isSEQ ID NO: 5, said process comprising the steps of:

-   -   i) cultivating a mammalian host cell comprising a polynucleotide        encoding the polypeptide having the amino acid sequence of SEQ        ID NO: 5 under conditions such that said polypeptide sequence is        expressed; and    -   ii) recovering from said host cell a homodimer wherein the amino        acid sequence of each polypeptide of said homodimer is SEQ ID        NO: 5.

The FGF21 protein of the present invention is a homodimer when expressedin mammalian cells. “Homodimer” as used herein, refers to two FGF21proteins of the present invention having the same amino acid sequence(for example SEQ ID NO: 5) that associate through non-covalentinteractions and intermolecular disulfide bonds in the Fc portion.

The present invention provides a homodimer of a FGF21 protein, whereinthe amino acid sequence consists of a first polypeptide fused to asecond polypeptide, wherein the first polypeptide comprises an IgG4 Fcportion, wherein the Fc portion consists of a hinge region, CH2 and CH3constant region domains of an antibody, the second polypeptide comprisesa FGF21 protein having the amino acid sequence of SEQ ID NO: 1, andwherein the C-terminus of the first polypeptide is fused to theN-terminus of the second polypeptide via a linker.

Furthermore, the present invention provides a homodimer of a FGF21protein, wherein the amino acid sequence consists of a first polypeptidefused to a second polypeptide, wherein the first polypeptide comprisesan IgG4 Fc portion having the amino acid sequence of SEQ ID NO: 14, thesecond polypeptide comprises a FGF21 protein having the amino acidsequence of SEQ ID NO: 1, and wherein the C-terminus of the firstpolypeptide is fused to the N-terminus of the second polypeptide via alinker.

The present invention also provides a homodimer of a FGF21 protein,wherein the amino acid sequence consists of a first polypeptide fused toa second polypeptide, wherein the first polypeptide comprises an IgG4 Fcportion having the amino acid sequence of SEQ ID NO: 14, the secondpolypeptide comprises a FGF21 protein having the amino acid sequence ofSEQ ID NO: 1, and wherein the C-terminus of the first polypeptide isfused to the N-terminus of the second polypeptide via a linker havingthe amino acid sequence of SEQ ID NO: 11.

The present invention provides a homodimer of a FGF21 protein, whereinthe amino acid sequence is

(SEQ ID NO: 5) ESKYGPPCPPCPAPEAAGGPSVFLFPPKPKDTLMISRTPEVTCVVVDVSQEDPEVQFNWYVDGVEVHNAKTKPREEQFNSTYRVVSVLTVLHQDWLNGKEYKCKVSNKGLPSSIEKTISKAKGQPREPQVYTLPPSQEEMTKNQVSLTCLVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFFLYSRLTVDKSRWQEGNVFSCSVMHEALHNHYTQKSLSLSLGGGGGSGGGGSGGGGSA HPIPDSSPLLQFGGQVRQRYLYTDDAQQTECHLEIREDGTVGCAADQSPESLLQLKALKPGVIQILGVKTSRFLCQRPDGALYGSLHFDPEACSFREDLKEDGYNVYQSEAHGLPLHLPGDKSPHRKPAPRGPARFLPLPGLPPALPEPPGILAPQPPDVGSSDPLRLVEPSQLRSPSFE.

The FGF21 protein of SEQ ID NO: 5 described above includes the IgG4 Fcportion sequence of SEQ ID NO: 14, the linker sequence of SEQ ID NO: 11that is identified in bold, and the FGF21 protein of SEQ ID NO: 1 thatis underlined.

Furthermore, the present invention provides a homodimer of a FGF21protein, wherein the amino acid sequence is

(SEQ ID NO: 15) ESKYGPPCPPCPAPEAAGGPSVFLFPPKPKDTLMISRTPEVTCVVVDVSQEDPEVQFNWYVDGVEVHNAKTKPREEQFNSTYRVVSVLTVLHQDWLNGKEYKCKVSNKGLPSSIEKTISKAKGQPREPQVYTLPPSQEEMTKNQVSLTCLVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFFLYSRLTVDKSRWQEGNVFSCSVMHEALHNHYTQKSLSLSLGGGGGSGGGGSGGGGSAHPIPDSSPLLQFGGQVRQRYLYTDDAQQTECHLEIREDGTVGCAADQSPESLLQLKALKPGVIQILGVKTSRFLCQRPDGALYGSLHFDPEACSFREX₁LX₂EDGYNVYQSEAHGLPLHLPGDKSPHRKPAPRGPARFLPLPGLPPALPEPPGILAPQPPDVGSSDPLRLVEPSQLX₃SPSFX₄X₅wherein X₁ is L or D, X₂ is L or K, X₃ is R or L, X₄ is L or E, and X₅is G or is absent. The present invention also provides a homodimer of aFGF21 protein of SEQ ID NO: 15, wherein the X₁ is D, X₂ is L or K, X₃ isL, X₄ is L, and X₅ is G. Furthermore, the present invention provides ahomodimer of a FGF21 protein of SEQ ID NO: 15, wherein X₁ is L or D, X₂is L or K, X₃ is R, X₄ is E, and X₅ is absent.

The present invention provides a homodimer of a FGF21 protein of SEQ IDNO: 15, wherein the FGF21 protein is selected from the group consistingof SEQ ID NO: 5, SEQ ID NO: 6, SEQ ID NO: 7, SEQ ID NO: 8, and SEQ IDNO: 9. The present invention also provides a homodimer of a FGF21protein of SEQ ID NO: 15, wherein the FGF21 protein is selected from thegroup consisting of SEQ ID NO: 8 and SEQ ID NO: 9. Furthermore, thepresent invention provides a homodimer of a FGF21 protein of SEQ ID NO:15, wherein the FGF21 protein is selected from the group consisting ofSEQ ID NO: 5, SEQ ID NO: 6, and SEQ ID NO: 7. The most preferred FGF21protein is SEQ ID NO: 5.

The present invention also relates to polynucleotides encoding theabove-described homodimer of a FGF21 protein of the present invention.

The present invention also provides a pharmaceutical compositioncomprising a homodimer of a FGF21 protein of the present invention andat least one pharmaceutically acceptable carrier, diluent, or excipient.

The present invention also provides a method of treating type 2diabetes, obesity, dyslipidemia, and/or metabolic syndrome in a patientcomprising administering to the patient a homodimer of a FGF21 proteinof the present invention.

Furthermore, the present invention provides a homodimer of a FGF21protein of the present invention for use in therapy. Preferably, thepresent invention provides a homodimer of a FGF21 protein of the presentinvention for use in the treatment of type 2 diabetes, obesity,dyslipidemia, and/or metabolic syndrome.

Furthermore, the present invention provides the use of a homodimer of aFGF21 protein of the present invention in the manufacture of amedicament for the treatment of type 2 diabetes, obesity, dyslipidemia,and/or metabolic syndrome.

The FGF21 proteins of the present invention may be glycosylated in theFc portion at a highly conserved N-glycosylation site. Furthermore, theFGF21 proteins of the present invention are a homodimer when expressedin mammalian cells. “Homodimer” as used herein, refers to two FGF21proteins of the present invention having the same amino acid sequence,for example SEQ ID NO: 5, that associate through non-covalentinteractions and intermolecular disulfide bonds in the Fc portion.

Full length human wild type FGF21 is a 208 amino acid polypeptidecontaining a 27 amino acid signal peptide. Mature human wild type FGF21comprises the full length polypeptide without the 27 amino acid signalpeptide, resulting in a 181 amino acid polypeptide (SEQ ID NO: 2).

The changes in amino acid positions of the FGF21 proteins of the presentinvention are determined from the amino acid positions in thepolypeptide of mature human wild type FGF21 (SEQ ID NO: 2) without anIgG4 Fc portion and a linker. For example, the IgG4 Fc portion of theFGF21 protein of SEQ ID NO: 5 includes amino acids 1 through 228, thelinker of the FGF21 protein of SEQ ID NO: 5 includes amino acids 229through 244, and the FGF21 protein of the FGF21 protein of SEQ ID NO: 5includes amino acids 245 through 424. Thus, a substitution describedherein as “A31C” refers to substitution of the amino acid Cys for thewild type amino acid Ala at position 31 of the mature human wild typeFGF21.

It is important to note that a substitution of one amino acid residue ina particular protein may affect the characteristics of the proteins as awhole, and that overall effect may be beneficial or detrimental to thepharmacological potency and/or pharmaceutical stability. For example,one amino acid substitution, P115W, increases the potency of the FGF21protein; however, P115W is also believed to contribute to theself-association that causes aggregation. Therefore, the overall effectis detrimental to the proteins, and thus the substitution P115W is notincluded in the FGF21 proteins of the present invention. Another examplerelates the amino acid substitution R175L, which increases the potencyof the FGF21 protein. However, FGF21 proteins having the R175Lsubstitution were found susceptible to proteolysis, thus the overalleffect was detrimental. To address the C-terminal proteolysis observedwith the FGF21 proteins of the present invention, amino acids atpositions 180 and 181 (L at position 180 and G at position 181) aresubstituted with the amino acid E at position 180 and the amino acid at181 is deleted. These modifications substantially decrease C-terminalproteolysis, but also reduce the pharmacological potency of the FGF21protein by 25-fold measured in the human 293 cell-βKlotho-SRE luc assay.Surprisingly, potency is restored by reverting the amino acid residue atposition 175 (R175L) back to the wild-type R. Therefore, the overalleffect of this substitution (R175L) is detrimental to the proteins, andthus the substitution R175L is not included in the preferred FGF21proteins of the present invention.

Certain FGF21 proteins of the present invention are potent, biologicallyactive proteins as demonstrated for SEQ ID NO:5 in Examples 2 and 3. Thepreferred FGF21 proteins of the present invention contain amino acidsubstitutions that together not only improve potency, but also arecompatible with other amino acid changes that, in turn, may provide forimproved stability characteristics and increased in vivo stability. Theamino acid substitutions in the preferred FGF21 proteins of the presentinvention that improve potency include D127K, S167R, and G174L (seeExamples 2 and 3).

Exposure of a concentrated protein solution of human wild type FGF21 toa pharmaceutical preservative, such as m-cresol, increases thepropensity of the protein to form aggregates. Structural stabilizationthrough the introduction of an additional disulfide bond improves thepreservative compatibility as well as the thermal stability of humanwild type FGF21. The FGF21 proteins of the present invention incorporatethe amino acid substitutions A31C and G43C that greatly improve thermalstability and preservative compatibility without compromising biologicalactivity. High potency FGF21 proteins that also include the A31C/G43Csubstitutions have been described previously. Those reported proteinsdisplay significantly improved preservative compatibility relative towild type FGF21, but they are still prone to aggregation in the presenceof preservative. This protein aggregation increases the risk ofimmunogenicity, thereby reducing the acceptability of the proteins as atherapeutic protein.

Fusion of FGF21 proteins to the Fc portion also makes self-associationmore prominent. This behavior may be due to the homodimeric structure ofthe Fc fusions that could lead to avidity, stabilizing self interactionand aggregation.

The preferred proteins of the present invention include the amino acidsubstitutions L98D and L100K, which surprisingly result in significantlylower high molecular weight aggregate formation at high concentrations.Advantageously, the amino acid substitutions L98D and L100K do notdecrease the potency of the proteins, but they do minimize thedetrimental aggregation problem.

A preferred commercial expression system for manufacture of the FGF21proteins of the present invention is the mammalian CHO-K1 cell line.However, the mammalian cell lines CHO-K1 and HEK293 may causepost-translational modifications to mature human wild type FGF21 throughsulfation of the tyrosine side chain at position 179. Sulfation oftyrosine residues at positions 179 and 180 (if present) decreasespotency and is an undesirable source of product heterogeneity. Thus,when an FGF21 protein having Tyr at position 179 and/or 180 is expressedfrom CHO-K1 or HEK293 cell lines, some proportion of the expressedproteins may be sulfated at position 179, others may be sulfated atposition 180, while others may be sulfated at both positions and some atneither position. This leads to a heterogeneous and unpredictableprotein population with decreased potency.

The preferred FGF21 proteins of the present invention include an aminoacid substitution that has resolved this detrimental sulfation. Thus,the amino acid substitution Y179F has been incorporated into theproteins. Y179F eliminates the sulfation resulting from production inCHO-K1 and HEK293 cells. Moreover, the amino acid substitution Y179F iscompatible with the other favored amino acid substitutions of thepresent invention, and is determined to be a neutral change with regardto potency.

Human wild type FGF21 is susceptible to proteolytic degradation in vivo.A major proteolytic fragment recovered from sera after intravenous orsubcutaneous injection of mice or cynomolgus monkeys with wild typeFGF21 is the fragment that terminates at position 171. The FGF21fragment spanning residues 1 to 171 has been determined to be ˜100-foldless potent in in vitro potency assays. Thus, eliminating thisproteolytic cleavage site may improve drug efficacy by increasingexposure to active drug. The amino acid substitution G170E has beenshown to significantly slow cleavage in mouse and virtually eliminateproteolysis at the 171 position when measured after 24 hours incynomolgus monkeys. The G170E substitution does not impact potency andis compatible with the desired physicochemical stability profile.Therefore, the amino acid substitution G170E is incorporated into theFGF21 proteins of the present invention.

Human wild type FGF21 is also susceptible to a carboxypeptidase producedin CHO-K1 manufacture, and the amino acid substitution A180E and aminoacid deletion at position 181 slows this processing, thereby reducingheterogeneity of the length of the protein expressed (i.e.,heterogeneity in the number of amino acid residues in the mature proteinexpressed by the cell line). Although the amino acid substitution A180Eand the amino acid deletion at position 181 do not eliminate C-terminalproteolysis in mammalian cell expression, it is quite effective atslowing proteolysis while maintaining potency in the context of otherdesired amino acid substitutions found in the FGF21 proteins of thepresent invention. In view of this advantageous characteristic, theamino acid substitution A180E and the amino acid deletion at position181 are incorporated into the preferred FGF21 proteins of the presentinvention.

The FGF21 proteins of the present invention are fused via a linker tothe Fc portion of an immunoglobulin. The Fc portion used for the FGF21proteins of the present invention is derived from an IgG4 Fc portion. Itis even more preferable that the FGF21 proteins of the present inventioncontain an Fc portion which is derived from human IgG4, but comprisesone or more substitutions compared to the wild type human sequence. Asused herein, the Fc portion of an immunoglobulin has the meaningcommonly given to the term in the field of immunology. Specifically,this term refers to an antibody fragment which does not contain the twoantigen binding regions (the Fab fragments) from the antibody. The Fcportion consists of a hinge region, CH2 and CH3 constant region domainsof an antibody.

It is well known in the art that mammalian expression of antibodiesresults in glycosylation. Typically, glycosylation occurs in the Fcportion of the antibody at a highly conserved N-glycosylation site.N-glycans typically attach to asparagine.

Thus, the FGF21 proteins of the present invention are derived from thehuman IgG4 Fc region of an immunoglobulin fused to a FGF21 protein ofthe present invention. Preferably, the Fc portion of the FGF21 proteincomprises the sequence of SEQ ID NO: 14:

(SEQ ID NO: 14) ESKYGPPCPPCPAPEAAGGPSVFLEPPKPKDTLMISRTPEVTCVVVDVSQEDPEVQFNWYVDGVEVHNAKTKPREEQFNSTYRVVSVLTVLHQDWLNGKEYKCKVSNKGLPSSIEKTISKAKGQPREPQVYTLPPSQEEMTKNQVSLTCLVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFFLYSRLTVDKSRWQEGNVFSCSVMHEALHNHYTQKSLSLSLG

The N-terminal amino acid of a FGF21 protein of the present invention isfused to the C-terminus of each heavy chain of the Fc portion via aglycine-rich linker (G-rich), designated by L, with the numberimmediately preceding the L referring to the number of repeating linkerunits separating the FGF21 protein from the Fc portion. A linker unit isdefined as a Gly-Gly-Gly-Gly-Ser sequence (SEQ ID NO: 10). The linkeroptionally contains an Ala linked to the final Ser if multiple linkerrepeats are used.

Fc portion of the FGF21 proteins of the present invention are preferablyfused together via 1, 2, or 3 repeats of the G-rich peptide linker,-Gly-Gly-Gly-Gly-Ser- (SEQ ID NO: 10), designated as 1L. AdditionalG-rich linkers of the present invention comprise the sequences-Gly-Gly-Gly-Gly-Ser-Gly-Gly-Gly-Gly-Ser-Ala (SEQ ID NO: 12), designated2L and -Gly-Gly-Gly-Gly-Ser-Gly-Gly-Gly-Gly-Ser-Gly-Gly-Gly-Gly-Ser-Ala(SEQ ID NO: 11), designated 3L. The most preferred glycine-rich linkerof the present invention is linker 3L,-Gly-Gly-Gly-Gly-Ser-Gly-Gly-Gly-Gly-Ser-Gly-Gly-Gly-Gly-Ser-Ala (SEQ IDNO: 11).

It is understood that the IgG4 Fc is comprised of the constant regionfrom both heavy chains of an IgG4 antibody. Thus, the FGF21 proteins ofthe present invention are comprised of an IgG4 Fc portion fused with twoFGF21 proteins having the same amino acid sequence via G-rich linkers toeach C-terminus of each IgG4 Fc portion polypeptide.

The pharmaceutical compositions of the FGF21 proteins of the presentinvention may be administered by any means known in the art that achievethe generally intended purpose to treat type 2 diabetes, obesity,dyslipidemia, and/or metabolic syndrome. The preferred route ofadministration is parenteral. The dosage administered will be dependentupon the age, health, and weight of the recipient, kind of concurrenttreatment, if any, frequency of treatment, and the nature of the effectdesired. Typical dosage levels can be optimized using standard clinicaltechniques and will be dependent on the mode of administration and thecondition of the patient and can be determined by a person havingordinary skill in the art.

The FGF21 proteins of the present invention are formulated according toknown methods to prepare pharmaceutically useful compositions. A desiredformulation is a stable lyophilized product that is reconstituted withan appropriate diluent or an aqueous solution of high purity withoptional pharmaceutically acceptable carriers, preservatives, excipientsor stabilizers [Remington, The Science and Practice of Pharmacy, 19thedition, Gennaro, ed., Mack Publishing Co., Easton, Pa. 1995].

The FGF21 proteins of the present invention may be formulated with apharmaceutically acceptable buffer, and the pH adjusted to provideacceptable stability, and a pH acceptable for administration. Moreover,the FGF21 compositions of the present invention may be placed into acontainer such as a vial, a cartridge, a pen delivery device, a syringe,intravenous administration tubing or an intravenous administration bag.

The term “dyslipidemia” means a disorder of lipoprotein metabolism,including lipoprotein overproduction or deficiency. Dyslipidemia may bemanifested by elevation of the total cholesterol, low-densitylipoprotein (LDL) cholesterol and the triglyceride concentrations,and/or a decrease in high-density lipoprotein (HDL) cholesterolconcentration in the blood.

The term “metabolic syndrome” is characterized by a group of metabolicrisk factors in one person. They include: abdominal fat—in most men, a40-inch waist or greater; high blood sugar—at least 110 milligrams perdeciliter (mg/dl) after fasting; high triglycerides—at least 150 mg/dLin the bloodstream; low HDL—less than 40 mg/dl; and/or, blood pressureof 130/85 or higher.

The term “obesity” is defined as a condition in which there is an excessof subcutaneous fat in proportion to lean body mass (Stedman's MedicalDictionary 28th edition, 2006, Lippincott Williams & Wilkins).

A “patient” is a mammal, preferably a human.

The term “treating” (or “treat” or “treatment”) means slowing, reducing,or reversing the progression or severity of an existing symptom,disorder, condition, or disease.

The term “therapeutically effective amount” refers to the amount or doseof a protein of the present invention, which, upon single or multipledose administration to a patient, provides the desired treatment.

The term “type 2 diabetes” is characterized by excess glucose productionin spite of the availability of insulin, and circulating glucose levelsremain excessively high as a result of inadequate glucose clearance.

The present invention may be practiced by referencing the followingexamples. However, this is not to be interpreted as limiting the scopeof the present invention. Furthermore, the FGF21 proteins of the presentinvention described and exemplified in the examples are expressed inmammalian cells, and therefore are a homodimer.

EXAMPLE 1 Expression of FGF21 proteins in CHOK1SV Cells

The FGF21 proteins of the present invention are produced in a mammaliancell expression system using CHOK1SV cells. Genes coding for the FGF21proteins of the present invention are sub-cloned into the GlutamineSynthetase (GS)-containing expression plasmid backbones (pEE12.4-basedplasmids). The cDNA sequence encoding the FGF21 proteins of the presentinvention is fused in frame with the coding sequence of preferred signalpeptide sequences to enhance secretion of the desired product into thetissue culture medium. The preferred signal peptide sequences are thepolypeptides as shown in the amino acid sequences SEQ ID NO: 3 and SEQID NO: 4.

The expression is driven by the viral cytomegalovirus (CMV) promoter.CHOK1SV cells are stably transfected using electroporation and theappropriate amount of recombinant expression plasmid, and thetransfected cells are maintained in suspension culture, at the adequatecell density. Selection of the transfected cells is accomplished bygrowth in methionine sulfoximine (MSX)-containing serum-free medium andincubated at 35-37° C. and 5-7% CO₂.

Clonally-derived cell lines are measured or determined by use of a flowcytometer. The expression of a FGF21 protein in mammalian cellsgenerally yields the natural N-terminal sequence, ESKY, i.e. without amethionine residue at the N-terminus, such as the FGF21 protein shown bythe amino acid sequence of SEQ ID NO: 5.

FGF21 proteins secreted into the media from the CHO cells may bepurified by Protein A affinity chromatography followed by preparativesize exclusion chromatography following standard chromatographictechniques. Briefly, FGF21 proteins from harvested media are capturedonto Mab Select Protein A (GE, Piscataway, N.J.) with PBS pH 7.4 runningbuffer; briefly washed with running buffer to remove non-specificallybound material; and eluted with 10 mM citrate pH 3.0. Fractionscontaining FGF21 proteins are pooled and pH is neutralized by adding1/10 volume of 1M Tris pH 8.0. The neutralized pool is concentrated andloaded onto a Superdex 200 size exclusion chromatography column (GE,Piscataway, N.J.) with PBS pH 7.4 mobile phase. Fractions containingmonomeric FGF21 protein (a covalently linked homodimer) are pooled,concentrated, and stored.

Alternatively, the cell free media containing FGF21 proteins may beheated to 50-60° C. for up to two hours, cooled, treated with detergent(Triton X-100) for viral inactivation, applied to a Mab Select Protein A(GE Healthcare) column, and washed successively with pH 7 Tris bufferedsolution with and without sodium chloride to remove non-specificallybound materials. The FGF21 protein is eluted from the column using 20 mMcitrate pH 3 and held at pH 3.4 to 3.7 for up to two hours for viralinactivation. The solution is adjusted to pH 4.8 to 5.2 by addition ofTris buffer and sodium chloride and mixed for at least 15 minutes.Precipitates that form are removed by depth filtration (Millipore). TheFGF21 protein is further purified by cation exchange chromatographyusing resins such as Poros HS 50 (Life Technologies) or SP Sepharose HP(GE Healthcare). The cation exchange column is eluted with sodiumchloride in a pH 5 sodium acetate buffered solution. The FGF protein maybe further purified by hydrophobic interaction chromatography on PhenylSepharose HP (GE Healthcare) by adjusting the pH from 7 to 8 using aTris buffer, addition of sodium sulfate and application to the columnfollowed by elution with a reversed concentration gradient of sodiumsulfate. Purified FGF21 protein can be passed through a viral retentionfilter such as Planova 20N (Asahi Kasei Medical) followed byconcentration/diafiltration into 10 mM citrate, 150 mM NaCl pH 7 usingtangential flow ultrafiltration on a regenerated cellulose membrane(Millipore).

EXAMPLE 2 3T3-L1-βKlotho Fibroblast Glucose Uptake Assay

3T3-L1-βKlotho fibroblasts are generated from 3T3-L1 fibroblasts byretroviral transduction of a CMV-driven mammalian expression vectorcontaining the coding sequence of wild type mouse βKlotho and ablasticidin resistance marker. Blasticidin-resistant cells are selectedafter growth for 14 days in the presence of 15 μM blasticidin, andβKlotho protein expression is verified by immunoblot with ananti-βKlotho antibody. The 3T3-L1-βKlotho fibroblasts are maintained inDulbecco's Modified Eagle Medium (DMEM) with 10% calf serum, and 15 μMblasticidin until plated for experimental use.

For glucose uptake, 3T3-L1-βKlotho fibroblasts are plated at 20,000cells/well in 96-well plates and incubated for 48 hours in DMEM with 10%calf serum. The cells are incubated for 3 hours in DMEM with 0.1% bovineserum albumin (BSA) with or without an FGF21 protein of interest,followed by 1 hour incubation in Krebs-Ringer phosphate (KRP) buffer (15mM Hepes, pH 7.4, 118 mM NaCl, 4.8 mM KCl, 1.2 mM MgSO₄, 1.3 mM CaCl₂,1.2 mM KH₂PO₄, 0.1% BSA) containing 100 μM 2-deoxy-D-(¹⁴C) glucose withor without an FGF21 protein. Non-specific binding is determined byincubation of select wells in Krebs-Ringer bicarbonate/Hepes (KRBH)buffer containing 1 mM 2-deoxy-D-(¹⁴C) glucose. The reaction isterminated by addition of 20 μM cytochalasin B to the cells and glucoseuptake is measured using a liquid scintillation counter.

Following the protocol essentially as described above, the in vitropotency (EC₅₀) of the homodimer of the FGF21 protein of SEQ ID NO: 5 inthe 3T3-L1-βKlotho fibroblast glucose uptake assay is determined to be0.070 nM.

EXAMPLE 3 Human 293 cell-βKlotho-SRE luc Assay

Construction of 293-βKlotho-SRE luc Reporter Cells:

HEK-293 cells (human embryonic kidney cells) are cultured at 37° C., 5%CO₂ in growth medium (GM) containing 10% fetal bovine serum (FBS) inDulbecco's modified Eagle's medium. Cells are cotransfected with aplasmid containing a CMV promoter driven human βKlotho expressioncassette and a plasmid containing a Serum Response Element (SRE) drivenluciferase expression cassette. The βKlotho expression plasmid alsocontains an SV40 promoter driven neomycin phosphotransferase expressioncassette to confer resistance to the aminoglycoside antibiotic G418.Transfected HEK-293 cells are selected with 600 μg/mL of G418 to selectfor cells where the transfected plasmids have been integrated into thegenome. Selected cells are cloned by dilution and tested for an increasein luciferase production at 24 hours post addition of FGF21. The clonedemonstrating the largest FGF21 dependant increase in luciferase ischosen as the cell line used to measure relative FGF21 proteinsactivity.

293-βKlotho-SRE luc FGF21 Activity Assay:

293-βKlotho-SRE luc cells are rinsed and placed into CD 293 suspensionculture media (Invitrogen). Cells are grown in suspension overnight at37° C., 6% CO₂, 125 rpm. Cells are counted, pelleted by centrifugation,and re-suspended in CD 293 media containing 0.1% BSA. Cells are placedin white 96 well plates at 25,000 cells per well. A four-fold serialdilution in CD 293/0.1% BSA is prepared for each FGF21 protein togenerate eight dilutions with final concentrations from 100 nM to 0.006nM. Dilutions are added to cells in triplicate and incubated for 16-20hours at 37° C., 5% CO₂. Luciferase level is determined by the additionof an equal volume of OneGlo™ luciferase substrate (Promega) andmeasuring relative luminescence. Data is analyzed using a four parameterlogistic model (XLfit version 5.1) to fit the curves and determine EC₅₀.

Following the protocol essentially as described above, the average invitro potency (EC₅₀) of the homodimer of the FGF21 protein of SEQ ID NO:5 in the human 293 cell-βKlotho-SRE luc assay is determined to be 0.51nM.

EXAMPLE 4 Physical Stability R175 and E180 Expression Heterogeneity

Production of a homogeneous protein product is desirable since it betterensures a consistent and well-characterized product. To assess productheterogeneity, a 10 μL aliquot of a sample is mixed with 90 μL of DPBS.The sample is analyzed by liquid chromatography-mass spectrometry(LC-MS), using the following conditions: the mobile phase A is 0.05%TFA, the mobile phase B is 0.04% TFA in acetonitrile, the column is aPLRPS 2.1×50 mm column, the injection volume is 15 μL.

TABLE 1 Gradient Conditions for Liquid Chromatographic Separation Time(min) 0 1 15 16 20 20.1 30 % B 5 35 40 90 90 5 5 Flow (μL/min) 200 200200 200 200 200 200A Waters Micromass LCT Premier™ mass spectrometer is set up to a massrange between 400 to 1990 amu, polarity ES+, capillary 3000, sample cone40 V, aperture 1 is 25 V, the source temperature is 105° C., cone gasflow is 50 L/hour, desolvation temperature is 150° C., and thedesolvation gas flow is 600 L/hour.

TABLE 2 LC/MS Characterization of FGF21 Proteins Product FGF21 Protein1-425 1-424 1-422 1-411 1-379 Homodimer of the FGF21 81.8% 11.8% 6.4%protein of SEQ ID NO: 8 Homodimer of the FGF21 48.8% 49.8% 1.2% 0.1%protein of SEQ ID NO: 9 Homodimer of the FGF21  100% protein of SEQ IDNO: 5

Table 2 reports the resulting heterogeneity in each FGF21 protein asdetermined by LC/MS method. The product 1-425 represents the full lengthFGF21 protein containing the IgG4 Fc portion, linker and FGF21 proteinfor the FGF21 protein of SEQ ID NO: 8 and the FGF21 protein of SEQ IDNO: 9. The FGF21 protein of SEQ ID NO: 8 and the FGF21 protein of SEQ IDNO: 9 differ only at position 100 with the FGF21 protein of SEQ ID NO: 8containing the wild type residue leucine and the FGF21 protein of SEQ IDNO: 9 containing the amino acid residue lysine (L100K) and both proteinshave identical C-termini. Both of these proteins are susceptible toC-terminal truncations, especially removal of the amino acid residueglycine at position 181. As shown in Table 2, less than 50% of thepurified product for the homodimer of the FGF21 protein of SEQ ID NO: 8and the homodimer of the FGF21 protein of SEQ ID NO: 9 is the intendedfull-length 1-425; the 1-424 fragment makes up the largest portion ofthe purified product. In addition, minor amounts of products 1-422,1-411, and 1-379 are also detected.

The FGF21 protein of SEQ ID NO: 5 has the amino acid residue at 181deleted in the genetic construct and amino acid residue 180 has beensubstituted to glutamic acid (E). These changes protect the C-terminusfrom degradation during CHO expression, resulting in 100% homogeneouspurified 1-424 product.

EXAMPLE 5 Physical Stability Self-Association at High Concentration

Protein aggregation and self-association is undesired since it couldpotentially exacerbate unwanted effects such as triggering an immuneresponse. Thus, maintaining the protein in a monomeric state (acovalently linked homodimer) is preferred. To test for the propensity ofFGF21 proteins to self-associate, proteins were dialyzed into thebuffers listed in Table 3 and analyzed by size exclusion chromatography(SEC) to determine the % high molecular weight (% HMW) of a 1.0 mg/mLsolution. % HMW is an indicator of protein aggregation andself-association.

The SEC separation method is performed on a Tosoh Bioscience 3000SWXL, 5micron column with dimensions 30 cm×0.78 cm. Mobile phase is 0.05 Msodium phosphate, 175 mM NaCl, pH 7 at a flow rate of 0.5 mL/minute. 1.0mg/mL samples are applied as 10 mcL injections and monitored at anabsorbance wavelength of 214 nm, whereas 75 mg/mL samples are applied as1 mcL injections and monitored at 280 nm.

TABLE 3 Self-Association Buffer 10 mM Citrate, 10 mM Citrate,Composition 150 mM NaCl 50 mM NaCl PBS Homodimer of the FGF21 protein ofSEQ ID NO: 8 HMW (%) 4.4% 4.4% 4.2% 1 mg/mL HMW (%) 13.7% 21.9% 14.6% 75mg/mL Homodimer of the FGF21 protein of SEQ ID NO: 9 HMW (%) 0.7% 0.8%0.8% 1 mg/mL HMW (%) 2.2% 3.5% 2.2% 75 mg/mL Homodimer of the FGF21protein of SEQ ID NO: 5 HMW (%) 0.4% 0.4% 0.4% 1 mg/mL HMW (%) 2.0% 3.6%2.2% 75 mg/mL

Table 3 illustrates 4-5% HMW for the homodimer of the FGF21 protein ofSEQ ID NO: 8 and <1% HMW for the homodimer of the FGF21 protein of SEQID NO: 9 and the homodimer of the FGF21 protein of SEQ ID NO: 5 at 1.0mg/mL for all buffer compositions. Samples were then concentrated to 75mg/mL to simulate a high concentration formulation and analyzed again bySEC to determine the % HMW. The homodimer of the FGF21 protein of SEQ IDNO: 8 variant contained 13.7-21.9% HMW at 75 mg/mL, whereas thehomodimer of the FGF21 protein of SEQ ID NO: 9 contained only 2.2-3.5%.Since the only difference between the FGF21 protein of SEQ ID NO: 8 andthe FGF21 protein of SEQ ID NO: 9 is a substitution at position 100(L100L versus L100K), this data demonstrates that L100K reduces HMWformation.

The FGF21 protein of SEQ ID NO: 5 also contains L100K in addition toother changes, and the lower % HMW is also observed in this homodimerprotein.

EXAMPLE 6 Physical Stability L100K Substitution and % High MolecularWeight

Physical stability of FGF21 proteins is determined as follows. Proteinsare dialyzed and prepared at 1-2 mg/mL in 10 mM Citrate pH7, 150 mM NaCland analyzed by SEC to determine the % HMW (Table 3: “Initial”).

The SEC separation method is performed on a Tosoh Bioscience 3000SWXL, 5micron column with dimensions 30 cm×0.78 cm. Mobile phase is 0.05 Msodium phosphate, 175 mM NaCl, pH 7 at a flow rate of 0.5 mL/minute.Initial low concentration samples are applied as 10 mcL injections andmonitored at an absorbance wavelength of 214 nm, whereas the 50 mg/mLsamples are applied as 1 mcL injections and monitored at 280 nm.

Next, proteins are concentrated to 50 mg/mL and analyzed again (t=0).The % HMW for the homodimer of the FGF21 protein of SEQ ID NO: 8increased from 4.5% to 9.3% upon concentration. The % HMW for thehomodimer of the FGF21 protein of SEQ ID NO: 9 increased from 0.9% to1.4% upon concentration. The % HMW for the homodimer of the FGF21protein of SEQ ID NO: 5 increased from 0.4% to 1.4% upon concentration.Thus, both the homodimer of the FGF21 protein of SEQ ID NO: 9 and thehomodimer of the FGF21 protein of SEQ ID NO:5 have lower initial % HMWand lower % HMW when proteins are formulated at 50 mg/mL than thehomodimer of the FGF21 protein of SEQ ID NO: 8. These data demonstratethe importance of the L100K mutation that is present in the FGF21protein of SEQ ID NO:9 and the FGF21 protein of SEQ ID NO: 5, but notpresent in the FGF21 protein of SEQ ID NO: 8.

The 50 mg/mL formulations are incubated for 4 weeks at 4° C., 25° C.,and 40° C. to assess longer-term stability under stress conditions. Asshown in Table 4, the % HMW is determined again at 4 weeks time (t=4weeks). The % HMW for the homodimer of the FGF21 protein of SEQ ID NO: 8increased from 9.3% to 16.0% at 40° C. The % HMW for the homodimer ofthe FGF21 protein of SEQ ID NO: 9 increased from 1.4% to 5.5% at 40° C.The % HMW for the homodimer of the FGF21 protein of SEQ ID NO: 5increased from 0.4% to 5.4% at 40° C. After 4 weeks at 25° C., levels of% HMW were only 3.3% for the homodimer of the FGF21 protein of SEQ IDNO: 9 and the homodimer of the FGF21 protein of SEQ ID NO: 5, whereasthey were 13.8% for the homodimer of the FGF21 protein of SEQ ID NO: 8.These data demonstrate the beneficial impact of including the L100Kmutation present in the FGF21 protein of SEQ ID NO: 9 and FGF21 proteinof SEQ ID NO: 5.

TABLE 4 % High Molecular Weight 50 mg/mL 50 mg/mL % HMW % HMW Initial (t= 0) (t = 4 weeks) Homodimer of the FGF21 protein of SEQ ID NO: 8 10 mMCitrate pH7, 150 mM NaCl 4.5% 9.3%  4° C. 12.1% 25° C. 13.8% 40° C.16.0% Homodimer of the FGF21 protein of SEQ ID NO: 9 10 mM Citrate pH7,150 mM NaCl 0.9% 1.4%  4° C. 3.3% 25° C. 3.3% 40° C. 5.5% Homodimer ofthe FGF21 protein of SEQ ID NO: 5 10 mM Citrate pH7, 150 mM NaCl 0.4%1.4%  4° C. 2.9% 25° C. 3.3% 40° C. 5.4%

EXAMPLE 7 Physical Stability Self-Association

Purified FGF21 protein of SEQ ID NO: 7 (which is the FGF21 protein ofSEQ ID NO: 5 having D98L) and purified FGF21 protein of SEQ ID NO: 6(which is the FGF21 protein of SEQ ID NO: 5 having K100L) were dialyzedinto 10 mM Citrate, 50 mM NaCl, pH6 buffer and concentrations aredetermined to be 12.9 mg/mL, 1.0 mg/mL, and 0.6 mg/mL, respectively.Each recovered sample from dialysis is analyzed by SEC to determine the% HMW (Table 5). The % HMW was <1% for all recovered dialysates. Next,samples are concentrated to 65-87 mg/mL using a 10,000 molecular weightcut-off, 4 mL Millipore spin concentrator. The concentrations for eachsample are shown in Table 5. After concentration, the % HMW isdetermined again by SEC using the concentrated protein.

As shown in Table 5, the % HMW for the homodimer of the FGF21 protein ofSEQ ID NO: 5 increased to 2.3% indicating a low level ofself-association that occurred at higher concentrations. In contrast,the % HMW for the homodimer of the FGF21 protein of SEQ ID NO: 7 (whichis the FGF21 protein of SEQ ID NO: 5 having D98L) and the homodimer ofthe FGF21 protein of SEQ ID NO: 6 (which is the FGF21 protein of SEQ IDNO: 5 having K100L) increased to levels of 8.0% and 14.2%, respectively.These data demonstrate a higher propensity for undesirableself-association when wild type L98 or L100 is included in the sequence.Thus, both L98D and L100K substitutions contribute to a decrease theself-association of the FGF21 protein of SEQ ID NO: 5. Furthermore, itis concluded that the presence of L100K in the absence of L98D (i.e. theFGF21 protein of SEQ ID NO: 7) is insufficient to fully minimizeself-association. Conversely, it is concluded that the presence of L98Din the absence of L100K (i.e. the FGF21 protein of SEQ ID NO: 6) isinsufficient to fully minimize self-association. Thus, the maximumeffect on reducing self association requires both L98D and L100Ktogether.

Upon dilution of concentrated proteins to 1 mg/mL, the % HMW decreasesdemonstrating that the self-association is reversible. Dilution of thehomodimer of the FGF21 protein of SEQ ID NO: 6 (which is the FGF21protein of SEQ ID NO: 5 having K100L) to 1 mg/mL results in the % HMWdecreasing from 14.2% to 2.0%. Dilution of the homodimer of the FGF21protein of SEQ ID NO: 7 (which is the FGF21 protein of SEQ ID NO: 5having D98L) to 1 mg/mL results in the % HMW decreasing from 8.0% to1.3%. When L98D and L100K are present together in the homodimer of theFGF21 protein of SEQ ID NO: 5, the % HMW decreases to 0.88% upondilution to 1 mg/mL, again demonstrating the more beneficial behaviorwhen L98D and L100K are combined.

TABLE 5 Self-Association Concentrate Dialysate Concentrate Diluted to 1mg/mL % % % FGF21 Protein mg/mL HMW mg/mL HMW mg/mL HMW Homodimer of the12.9 0.75 76 2.3 1.0 0.88 FGF21 protein of SEQ ID NO: 5 Homodimer of the0.6 0.78 87 14.2 1.0 2.0 FGF21 protein of SEQ ID NO: 6 Homodimer of the1.0 0 65 8.0 1.0 1.3 FGF21 protein of SEQ ID NO: 7

EXAMPLE 8 Glucose Lowering in Ob/ob Mouse Model

Male ob/ob mice and age-matched ob/m (lean) controls are 7 weeks of ageupon arrival and 8-9 weeks of age at initiation of treatment. Uponarrival, all mice are single housed and allowed to acclimate for 1-2weeks before the start of treatment. The mice are fed Purina Rodent Chow5015 and given house water from an auto-water apparatus ad libitum. Themice are housed in 12-hour light/dark cycle with ambient temperature setat 75° F. One to two days prior to initiation of treatment, bloodsamples are collected via tail bleed. Blood glucose levels are measuredusing an Accu-Check Avivia blood glucose meter (Roche) and serum samplesare collected for the assay of insulin using the Meso Scale mouse/ratinsulin assay kit. On the day of treatment initiation (day 0), the miceare sorted into groups based on the pretreatment body weight, bloodglucose, and serum insulin (BRAT sorting software). On day 0 and day 3,mice are dosed SQ with 0.1 to 30 nmol/kg of the homodimer of the FGF21protein of SEQ ID NO: 5, in a volume of 10 ml/kg. Dosing vehicle issterile PBS (HyClone DPBS/Modified-Calcium-Magnesium) containing 0.03%mouse serum albumin (MSA; Sigma A3139). Blood glucose is measured dailyfor 7 days and the AUC is determined. ED₅₀ calculations for the glucoselowering are based on the AUC. Liver homogenates are collected at thetime of sacrifice and liver triglycerides are measured on the HitachiModular P clinical analyzer.

On day 7, vehicle treated mice were hyperglycemic with mean bloodglucose levels measured at 387±63.0 mg/dl (mean±SEM), while ob/m leancontrol mice had blood glucose levels of 162±9.0 mg/dl (mean±SEM). Thehomodimer of the FGF21 protein of SEQ ID NO: 5 lowered blood glucose tolevels comparable to the ob/m lean controls. The ED₅₀ of the homodimerof the FGF21 protein of SEQ ID NO: 5 was 2.796 nmol/kg (95% confidenceinterval=1.1-7.0).

We claim:
 1. An FGF21 protein consisting of a first polypeptide fused toa second polypeptide via a linker, wherein: a.) the first polypeptideconsists of an IgG4 Fc portion, b.) the second polypeptide has the aminoacid sequence of SEQ ID NO: 1, and c.) the linker fuses the C-terminusof the first polypeptide to the N-terminus of the second polypeptide. 2.The FGF21 protein of claim 1, wherein the IgG4 Fc portion has the aminoacid sequence of SEQ ID NO:
 14. 3. An FGF21 protein having the aminoacid sequence (SEQ ID NO: 5)ESKYGPPCPPCPAPEAAGGPSVFLFPPKPKDTLMISRTPEVTCVVVDVSQEDPEVQFNWYVDGVEVHNAKTKPREEQFNSTYRVVSVLTVLHQDWLNGKEYKCKVSNKGLPSSIEKTISKAKGQPREPQVYTLPPSQEEMTKNQVSLTCLVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFFLYSRLTVDKSRWQEGNVFSCSVMHEALHNHYTQKSLSLSLGGGGGSGGGGSGGGGSAHPIPDSSPLLQFGGQVRQRYLYTDDAQQTECHLEIREDGTVGCAADQSPESLLQLKALKPGVIQILGVKTSRFLCQRPDGALYGSLHFDPEACSFREDLKEDGYNVYQSEAHGLPLHLPGDKSPHRKPAPRGPARFLPLPGLPPALPEPPGILAPQPPDVGSSDPLRLVEPSQLRSPSFE.


4. A homodimer of two FGF3 proteins of claim
 3. 5. The homodimer ofclaim 4, wherein each FGF21 protein is glycosylated.
 6. A pharmaceuticalcomposition comprising the homodimer of claim 5, and at least onepharmaceutically acceptable carrier, diluent, or excipient.
 7. A methodof lowering blood glucose in a patient having type 2 diabetes, obesity,dyslipidemia, or metabolic syndrome, comprising administering ahomodimer of claim 5 to a patient in need thereof.
 8. A DNA moleculeencoding an FGF21 protein, wherein the FGF21 protein has the amino acidsequence of SEQ ID NO:
 5. 9. A mammalian host cell transformed with theDNA molecule of claim 8, which cell is capable of expressing an FGF21protein, wherein the FGF21 protein has the amino acid sequence of SEQ IDNO:
 5. 10. A process for producing a homodimer of two FGF21 proteinscomprising the steps of: i) cultivating a mammalian host cell comprisinga polynucleotide encoding a FGF21 protein having the amino acid sequenceof SEQ ID NO: 5 under conditions such that said FGF21 protein isexpressed; and ii) recovering from said host cell the homodimer whereinthe amino acid sequence of each FGF21 protein is SEQ ID NO: 5.